Page 1 of 2page number not for citation purposes Available online http://ccforum.com/content/10/2/409 In a prospective observational study that included 60 consecutive patients over a 10
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Available online http://ccforum.com/content/10/2/409
In a prospective observational study that included 60
consecutive patients over a 10-year period, Page and
coworkers [1] studied the effects of early continuous
veno-venous haemodiafiltration (CVVHDF) during sepsis-induced
multiple organ failure In two-thirds of the patients rapid
metabolic improvement during CVVHDF was associated with
circulatory improvement and a low mortality rate, whereas lack
of metabolic improvement after 12 hours of CVVHDF (mainly
based on changes in base excess) was associated with a
100% mortality rate The authors concluded that early
CVVHDF may improve the prognosis of sepsis-related multiple
organ failure, and that failure to correct metabolic acidosis
rapidly during the procedure is a strong predictor of mortality
In that study, metabolic acidosis was assessed using base
excess values, and the authors highlighted the influence of
individual changes 6-12 hours after initiation of CVVHDF on
predicted outcome However, despite the findings reported,
the usefulness of base excess is questionable First, because
of the high incidence of circulatory failure occurring after
several days of hospitalization, base excess may be
influenced by large volume crystalloid infusion, resulting in
altered protein status Second, the link between base excess
and lactate concentration was weak (r2= 0.36 for the
patients studied) We believe that lactate values may be more
important in predicting outcome than base excess Indeed, it
is widely accepted that early lactate clearance is associated with improved outcomes in septic shock [2] and that lactate levels are not affected by CVVHDF [3] In the study by Page and coworkers [1] one cannot exclude the possibility that the lack of improvement in base excess in the nonresponder group was linked to persistent lactate production, and so metabolic improvement during the procedure is not necessarily superior to the trend in blood lactate as a predictive tool
Although beneficial effects of early high-volume isovolaemic haemofiltration have been reported [4,5], such benefits may not be realized with standard volume procedures [6] Furthermore, a randomized study design would have enhanced the strength of the findings reported by Page and coworkers [1] Moreover, we believe that a comparison between observed mortality and that predicted by Simplified Acute Physiology Score (SAPS) II does not permit one to draw conclusions regarding whether CVVHDF has a beneficial effect [7], at least for secondary shock, in view of the poor performance of physiological scores for delayed acute renal failure
In summary, this study of standard volume CVVHDF in sepsis [1] is undoubtedly important, but its findings should be viewed with caution until further investigations have been undertaken
Letter
Early venovenous haemodiafiltration for sepsis-related multiple organ failure
Frédéric M Jacobs and François G Brivet
Service de Réanimation Médiacle, Hôpital Antoine Béclère-Assistance, Publique Hôpitaux de Paris, Paris, France
Corresponding author: Frédéric M Jacobs, frederic.jacobs@abc.aphp.fr
Published: 27 April 2006 Critical Care 2006, 10:409 (doi:10.1186/cc4906)
This article is online at http://ccforum.com/content/10/2/409
© 2006 BioMed Central Ltd
See related research by Page et al., http://ccforum.com/content/9/6/R755
Authors’ response
Antoine Vieillard-Baron and François Jardin
We thank Drs Jacobs and Brivet for their remarks
Beyond the pertinence of comparing predicted mortality by
SAPS II with observed mortality, the overall mortality rate of our
population was 53%, which is far from the 85% and 92%
mortality rates previously reported in similar populations [8,9]
Moreover, in a previous prospective study conducted by Dr Brivet himself and his coworkers [10], the mortality rate in patients who exhibited acute renal failure related to septic shock was as high as 79.4%, whereas the mean SAPS score was 19, corresponding to a mean SAPS II score of about 50, which is much lower than the SAPS II score in our population [1]
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Critical Care Vol 10 No 2 Jacobs and Brivet
Drs Jacobs and Brivet consider base excess to be of
questionable usefulness in assessing metabolic acidosis
However, as they point out above, it appears not to perform
so poorly because the change in base excess after 12 hours
of CVVHDF strongly discriminated those patients with a
100% mortality rate They also suggest that base excess
could in part reflect hyperchloraemic acidosis induced by
large volume crystalloid infusion However, as reported in
Table 2 of our report [1], plasma chloride concentration was
in the normal range and did not differ between the two
groups On the other hand, we agree that base excess
reflects not only lactic acidosis but also renal acidosis
However, in our opinion, this is better for evaluating the
severity of illness in such patients because it takes into
account two of the main parameters that have been reported
to be associated with high mortality rates in sepsis (i.e renal
failure and persistent lactic acidosis) [11]
Drs Jacobs and Brivet point out that we did not use
high-volume haemofiltration It is true that we used a flow rate of
only 2000 ml/hour, leading to an average convection
exchange of 28 ml/kg per hour However, because we
performed CVVHDF, we also used 1000 ml/hour of dialysis,
leading to a ‘global exchange’ of about 40 ml/kg per hour
Finally, Drs Jacobs and Brivet suggest that the lack of
improvement in base excess in nonresponders may have been
linked to persistent lactate production Indeed, it was caused
by persistent lactate production! However, on reading the
latter comment by Drs Jacobs and Brivet, we wonder whether
they completely understood our report, in which CVVHDF is
proposed to be an additional means to ameliorate circulatory
failure, not a treatment for acidosis per se.
Competing interests
The authors declare that they have no competing interests
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